In order to seal between a rod centered on an axis and extending from a passage or through a hole in a situation where the rod axis moves relative to the support forming the passage or hole, recourse is usually had to an elastomeric membrane or cuff. German utility model 7,214,594 describes the classic such system. Here the membrane is generally planar and annular. Its inner periphery is clamped between two washers on the rod and its outer periphery is clamped between two parts of the support. Such an arrangement can only permit limited pivoting or swiveling of the rod relative to the support, and cannot compensate for any appreciable rotation of the rod about its axis.
Similarly U.S. Pat. No. 2,477,882 of L. LaBrie describes a seal engaged between a brake-pedal push rod and a master-cylinder piston. This seal is also annular and has an outer surface clamped on the support and an inner periphery that closely engages the cylindrical outer surface of the rod, but that can slide on same, permitting it to rotate or move axially. Such an arrangement can only permit limited nonaxial deflection of the rod and is fairly complex.
Another arrangement permitting substantial axial displacement and rotation of the rod is described in Austrian patent No. 166,359 filed by Fiat with a claim to an Italian priority of 27 June 1945. Here the rod passes through a soft elastomeric seal ring whose outer face is adhered to the support around the passage and whose opposite inner face is engaged by a washer against which a spring bears. This compresses the seal ring axially and forces its inner periphery against the outer surface of the rod, so that same can move axially or rotate, but cannot be tilted much from a position passing perpendicularly through the seal ring. In addition such an arrangement, if tightened enough to seal with the rod passing perpendicularly through it, becomes very tight if the rod is tilted, greatly inhibiting such motion of the rod.
A considerable amount of deflection is possible with the system described in French patent No. 2,272,315 filed by R. B. Bowen et al with a claim to the priority of U.S. application 473,139 filed 24 May 1974. In this system the lever can move all about in a hole over a relatively wide range. The wall through which the passage is formed has a part-spherical inner surface whose center of curvature lies at the pivot point for the lever. A rigid element having a part-cylindrical outer surface is carried on the shaft and engages the inner surface of the support wall, urged thereagainst by a spring, so that a sliding joint is formed. This arrangement makes a fairly good seal, but takes up quite a bit of space while being rather expensive and complex to manufacture.